Hypodermic syringe and ventable closure means



y 8, 1963 R. K. MOCONNAUGHEY ET AL 3,091,240

TABLE CLOSURE MEANS HYPODERMIC SYRINGE'AND VEN Filed May 29, 1958 2 Sheets-Sheet 1 INVENTOR ATTORNEY 1963 R. K. MCCONNAUGHEY ETAI. 3,091,240

HYPODERMIC SYRINGE AND VENTABLE CLOSURE MEANS Filed May 29, 1958 2 Sheets-Sheet 2 I N VE N TOR ATTORNEY states This application relates primarily to disposable hypodermic syringe cartridge constructions, and particularly to me ans of sealing, stoppering or otherwise closing the end of the barrel of such cartridges adjacent the hypodermic needle with a entable closure, and to hypodermic syringe cartridges embodying such means. The structures described are, however, adapted to use also in other containers having a cylindrical portion communicating with [an opening at one end.

In the design of disposable hypodermic syringe packages, especially syringe packages using glass barrels, one of the problems to be met has been the devising of simple and inexpensive means whereby, although contact between the medicament and the channel of the needle is prevented during the period of storage and handling, the user of the syringe can readily, and with a minimum of manipulation, bring the channel of the needle into communication with the medicament chamber so that the contents may be ejected or material may be drawn through the needle by aspiration to check the placement of the needle point. An objective of this invention is to provide means .of accomplishing these results in disposable syringe cartridges of the types commonly used in packaging liquid injectable medicaments and to provide syringe cartridges embodying such means, in which, until the syringe is to be used, the medicament in the cartridge is sealed off from contact with the needle afiixed to the cartridge in :a manner than will enable the user then to aspirate the syringe, and to eject its contents, each with a minimum of manipulation and by movements typical of the usual operation of hypodermic syringes having an unobstructed passage between the medicament chamber and the channel of the needle.

It is an additional objective of this invention to afford, in a disposable springe cartridge having the needle permanently afiixed, lal'l occlusion of the passage from the medicament chamber to the needle channel that will keep the medicament from being ejected from the cartridge prematurely as a result of changes in pressure normally encountered in the handling and storing of such cartridges, without the necessity of using an occluding plug or sheath over the point of the needle such as is commonly used in needle attached cartridges now in use.

It is a further objective of the invention to provide a closure [that will achieve the objectives stated above and that can be made and assembled into the container in conformity with established filling land stoppering techniques at a cost which does not substantially exceed the cost of ordinary stoppers or sealing gaskets. Such ordinary stoppers or gaskets have the disadvantage in the case of needle-attached hypodermic syringes, of either permitting the medicament in the cartridge access to the channel of the attached needle or requiring utilization, as a barrier between the medicament chamber and the attached needle, of an imperforate membrane which must be perforated, prior to use of the syringe, by puncturing it with a needle or stylet or other puncturing means.

These and other objectives of the invention and the manner in which such objectives are accomplished will become more readily apparent from the following description of the invention, read in conjunction with the accompanying drawings.

atent ice The essential element of the invention is a perforated or slit membrane, held in position across the bore of a cylindrical portion of the container by any of various means hereafter described and so dimensioned that, under pressures or pulling forces less than those normally generated by intentional actuation of the plunger piston to eject the contents of the cartridge or to aspirate the syringe, the edges or lips of each perforation or slit will remain close and thereby provide a seal against the passage of con-tents of the cartridge but, upon application of pressures or pulling forces equal to or greater than those normally applied in intentionally ejecting the contents of a hypodermic syringe or in aspirating such a syringe, will open to permit the passage, in either direction, of fluent materials such as liquids, gases or powders. The variations described are primarily variations in the manner and means of positioning and holding such a membrane across the bore of the barrel of the container or across a cylindrical passage communicating with an opening at one end of the container, and in the position where it is so held.

FIGURE 1 is a cross-section side view of one form of the invention wherein the perforated or slit membrane closes one end of the shaft of a hollow cylindrical stopper, at the other end of which is an outwardly extending annular flange.

FIGURE 1(a) is [a front end view of the form of the invention shown in FIGURE 1, in which the dotted lines indicate the opening of the lips of the check valve slit upon application of pressure to either the front or the rear face of the membrane.

FIGURE 1(b) is a cut-away side view of a hypodermic syringe with the form of the invention shown in FIG. 1 in place in the neck of the cartridge barrel.

FIGURE 2 is a cut away side view of another form of the invention similarly in position in the neck of a hypodermic syringe cartridge.

FIGURE 3 is a cut away side View of a third form, similarly in place in the neck of a hypodermic syringe cartridge.

FIGURE 4 is a cut away side view of a fourth form similarly in place in the neck of a hypodermic syringe cartridge.

FIGURE 5 is a cut away side view, in position in a spyringe cartridge, of an alternative form made integral with a floating piston which consists of an annulus with a central cylindrical opening coaxial with the barrel and with the perforated or slit elastic memberane closing said opening, the piston holding the perforated or slit membrane in position across the bore of the barrel.

FIGURE 5(a) is an enlarged view of the slit membrane piston of FIGURE 5. The piston shown in FIG- URE 5(a) illustrates :an alternative position of the membrane intermediate the ends of the opening in the annulus rather than at either end of the opening.

FIGURE 6 is a syringe cartridge embodying a variant application of the form shown in FIGURE 5.

FIGURE 7 shows a syringe cartridge embodying another variant application of the form shown in FIG- URE 5.

FIGURE 8 shows one form of the invention in a straight cylindrical tube cartridge.

FIGURE 9 shows another variation in which the membrane is positioned in a manner similar to the form shown in FIGURE 4, but which has l3. sleeve projecting below the membrane into the neck of the cartridge barrel to facilitate the procedures for fastening the needle assembly to the cartridge.

FIGURE 9(a) shows in cross section the neck and forward portion of a hypodermic syringe cartridge embodying the form of closure shown in FIGURE 9.

The form of the invention shown in FIGURES 1, 1(a) and 1(b) illustrates its basic construction and functioning.

This form consists of a one-piece integrally formed stopper and sealing ring gasket of rubber or other material having similar elastic characteristics and having (A) a flange 1 around the upper rim of the stopper, the forward face of the flange being preferably, but not necessarily, crowned, beveled or tapered into roughly triangular or half-round cross section so that when the needle assembly is pressed downward to seal the cartridge, as illustrated in FIGURE 1( b), the elastic material of the flange has room to flow both inward and outward without occluding the passage 2 which projects rearward through the shaft 3 from the forward face of the stopper; and having (B) a membrane 5 across the passage 2, the membrane 5 being perforated by one or more holes, preferably, but not necessarily, slits 6.

The thickness of the membrane 5 may be varied in relation to its own diameter and the diameter of the passage 2, to the stiffness of the elastic material from which the stopper is made, and to the length of the slit 6 (if a slit is used), so that the lips formed by the edges of the slit or the edges of the perforation will open in either direction upon application of that amount of pressure suitable for the particular use to which the device is to be put. By thus varying one or more of the following specifications, (a) the stiffness of the material from which the stopper is made, (b) the diameter of the membrane, (0) the thickness of the membrane, (d) the length of the slit, the resistance of the valve formed by the perforation or slit in the membrane to pressures may be varied to achieve various optimum combinations that will provide a seal sufiicient- 1y tight to preclude the passage, outward or inward, of gases, liquids of varying viscosities and powders or suspensions, under pressures normally anticipated from either outside or inside the container in the absence of intentional actuation of the plunger. Thus it is possible to provide a more or a less sensitive valve which will open only when subjected to approximately predetermined pressures. In this manner the stopper may be adapted, by changes in one or more of these specifications, to meet varying requirements.

Assembly of this form of the stopper to the cartridge is accomplishedin the manner commonly used in corking or stoppering any container with a flanged stopper, by inserting the shaft 3 of the stopper into the container and pressing it downward until the flange 1 abuts the forward rim 15 of the container 11. Because of the perforation or slit 6'in the membrane at the base of the stopper, it is, to a large extent, self-venting upon assembly in this manner. Especially if the cartridge has been filled to a point Where there is little air ahead of the medicament in the chamber, the increase in relative pressure inside the container, resulting from movement of the stopper into the neck, tends to cause the valve to open and permit entrapped air to escape to an extent that pressure on opposite sides of the membrane sufiiciently approaches equality to permit the lips or edges of the valve to return to their closed position so as to form an effective seal between the inside and the outside of the container, the friction of the outer surface of the stopper against the neck being suflicient to hold the stopper in place. If it should be desirable, the stopper can be inserted into the opening of the container by a tool so formed as to provide a dilator projected through the slit or perforation to provide positive venting of the chamber, the tool, including the dilator being withdrawn when the stopper is in place. As a further alternative, the shaft of the stopper may be provided with longitudinal grooves or ridges (17, FIGURES 9 and (a)) on its outer surface to vent the container as the stopper is being inserted. The stopper may also be inserted with the membrane imperforate if suitably vented and the slit or perforation may be made thereafter by a pointed or edged cutting or puncturing device. If desirable the slit or perforation may be made by the filling needle in case the medicament is placed into the cartridge through the membrane.

The stopper may be inserted after the cartridge, with the plunger piston 7 in place, has been filled to the required level with medicament. Or, if preferred, the empty cartridge may be stoppered first and the medicament introduced through the slit or perforation (or by a filling needle making its own perforation). As a third alternative, the empty cartridge may be stoppered, the medicament being introduced thereafter from the rear of the cartridge and the cartridge being closed from the rear by the introduction of the plunger piston 7 suitably vented. In the case of this last alternative the perforation or slit in the membrane may be made either before or after the medicament is placed in the cartridge. As a still further alternative, the empty cartridge can be stoppered and the plunger piston placed in position, and the medicament can be introduced thereafter by suitable filling and venting needles inserted through the membrane or through the plunger piston, or between the outer circumference of the plunger piston and the inner wall of the barrel.

At a suitable point in the filling sequence, depending in part upon which of the several methods of filling described above is used, the needle assembly is applied and (if a crimped on or rolled on connector is used, with a necked cartridge) the skirt of the connector cap 18 is rolled or crimped under the rear face of the lip of the barrel, sufiicient pressure being applied in pressing the needle assembly onto the cartridge to cause the flange 1 to flow sufliciently to afiord a tight seal around the front rim of the cartridge. Such seal would be supplemented by any seal provided by the shaft of the stopper held firmly in the neck of the barrel.

The cartridge may also be filled, if desired, by moving the plunger piston of a fully assembled but empty cartridge forward as far as desired and inserting the point of the needle'into the material to be introduced into the cartridge and then, by drawing the plunger piston back, sucking the material through the needle and through the valve in the stopper formed by the perforation or slit into the medicament chamber (9, FIGURE 1(b) Where the valve will hold it against ejection until the user resumes reciprocal operation of the plunger shaft.

When it is desired to eject the contents of the cartridge, the plunger piston 7 is pressed forward by the plunger shaft 8, the pressure of the column of liquid in the medicament chamber (9, FIGURE 1(5)) in the barrel ll} of the cartridge (and of any air entrapped ahead of the liquid behind the membrane 5) forces the lips or edges of the slit 6 or perforation in the membrane to open forward and outward as illustrated by broken lines in FIGURE 1, permitting the contents to pass through the neck of the cartridge into the channel of the needle and thence through the needle into the subject of the injection.

If it is desired to aspirate the syringe to determine whether it'is properly positioned for injection, or to draw material through the needle into the cartridge for any other reason, this may be done by drawing the plunger piston rearward in the barrel, thus reducing the relative pressure on the inner face of the membrane 5 whereupon air, liquid, powder or any other fluent substance outside the membrane, pressing firmly rearward against the membrane, forces open the lips or edges of the slit 6 or perforation in the membrane, permitting the substance ahead of the membrane to pass through the slit or perforation into the medicament chamber of the barrel 10.

In the variant illustrated in FIGURE 2 there is a widened cavity 2a in the lower segment of the passage 2. This construction, in a stopper having a relatively long plug or shaft and having the perforated membrane at 01' adjacent the end of the shaft remote from the flange, tends to facilitate the functioning of the two-way check valve provided by the slit or perforation 6 in the membrane 5 by permitting a larger diameter membrane and hence a higher degree of flexibility in a membrane of the same thickness, as well as a higher degree of flexibility in the walls of the stopper immediately adjacent the membrane, without, however, impairing the ease of assembly of the stopper into the cartridge, as would occur if a thin wallsection were used throughout the full length of the stopper shaft making it flaccid. In addition, this form of construction in a relatively long shafted stopper diminishes, in contrast to a thin walled stopper with a relatively larger passage, the residue of medicament remaining in the passage 2 after the piston has reached the bottom of its stroke. Otherwise, the variant shown in FIGURE 2 functions in a manner similar to that shown in FIGURES l, 1(a) and 1( b).

The variant shown in FIGURE 3 is generally similar to that shown in FIGURES 1, 1(0), 1(1)) and 2 except that it is used in combination with a cylindrical rearward projecting element 12 in the needle assembly, which serves to accentuate the seal of the stopper in the neck of the barrel and to assure dilation of the passage 2 against any tendency to close as a result of flow of the elastic material of the stopper when downward pressure is applied against the flange 1 in fastening the needle assembly to the cartridge. The form shown in FIGURE 3 also illlustrates a bead 4 or ring formed around the outer edge of the rearward face of the stopper to stiffen the structure at that point so as to facilitate assembly and protect the membrane 5 agains distortion.

The form shown in FIGURE 8 is a variant of the form shown in FIGURE 3 wherein a cylindrical element 12, of the needle assembly extends rearward into the cavity of the stopper, dilating the cavity and compressing the wall of the stopped against the wall of the barrel, thereby accentuating the seal of the stopper in the barrel. In the form shown in FIGURE 8 the rearward extending element is a part of the needle hub rather than a part of the needle itself as appears in FIGURE 3. In addition FIGURE 8 illustrates the use of the veritable closure means of the invention in conjunction with a straight cylindrical container, as distignuished from the necked containers shown in others of the drawings.

The form shown in FIGURE 4 is a membrane washer similar in general construction and function to the forms shown in FIGURES l, 1(a), 1(b), 2 and 3, except that it has no shaft or plug portion projecting into the neck of the cartridge, the membrane 5 being positioned straight across between the thicker ring or annulus 21, which serve as a gasket or washer to seal the cartridge around the forward rim. In connection with this form of membrane washer, the hub 31 or other structure of the needle assembly immediately forward of the membrane may be recessed to afiord additional space, forward of the membrane, into which the lips or edges, of the slit or perforation may move when, under pressure from the rear, resulting from actuation of the plunger piston, they are impelled to open forward to permit the flow of liquid inside the cartridge through the perforation or slit 6, thence into the recess 32 forward of the membrane and through the channel of the needle 30.

FIGURES 9 and 9(a) illustrate a variant in which the membrane 6 is positioned adjacent the flange 1, as in FIG- URE 4, but which has an open cylindrical shaft 93 below the membrane and the flange, the shaft projecting into the neck of the barrel to hold the stopper in position in the neck, thereby facilitating assembly of the needle to the cartridge. The outer surface of the shaft may have flutes or ridges 94 to vent the stopper during assembly.

In the form illustrated in FIGURE 5 the valving mechanism is constructed and functions in basically the same manner as the valving mechanism in the forms shown in the other figurse previously described, but the means of holding the perforated or slit membrane across the bore of the barrel differs. In this form the membrane is not held fixed firmly in position as in the case of the forms previously described. Instead, it is formed integrally with a floating piston 22 which, in use in the barrel of a cylindrical container such as a syringe cartridge barrel, is mounted reciprocally in the barrel.

By varying the stiffness of the membrane in the form illustrated in FIGURE 5, this floating venting piston or separator may be made and assembled in the container in a manner that will enable it to function more readily to permit ejection of the contents of the cartridge than to permit material adjacent the forward face of he membrane to be drawn rearward through the slits or perforations into the medicament chamber. If, for example, forward movement of the floating piston is arrested by a shoulder formed by a neck at one end of the barrel or by other means of impeding its forward movement and the relative pressure required to open the lips or edges of the slit or perforation is greater than the pressure required to move the floating piston reciprocally in the barrel, the piston will move rearward in the barrel when the plunger piston is drawn rearward before the pressure is sufiicient to open the slits or perforations rearward. In such a case when the plunger piston 7 is drawn rearward the floating piston 22 will move rearward a commensurate distance, and material adjacent the point of the needle will be drawn into the chamber 51 ahead of the floating piston 22 where the results of aspiration will be visible through the walls of the transparent neck and forward portion of the barrel of the cartridge instead of being drawn through the perforation or slit in the membrane and mingled with the medicament in the main chamber 50 in the barrel of the cartridge.

This may be of critical advantage Where the medicament chamber is charged with an opaque suspension or a colored solution that would obscure observation of the product of aspiration if it were drawn into the medicament.

It would flso permit the cartridge to be loaded partially with one substance placed in the chamber 50 behind the venting piston, and partially with another substance placed into the forward chamber 51 ahead of the venting piston where it would be held separate from that previously loaded into the rear chamber 50 until it is desired to eject one or both. For example, two or more measured doses of the same medicament to be administered to the same patient at prescribed intervals could thus be packaged in one cartridge.

As in the case of the forms previously described, by varying the stiffness of the material of which the floating membrane piston is made, the thickness of the membrane and the diameter of the membrane as described above in the description of the form shown in FIGURE 1, or by varying the tightness of fit of the floating membrane piston in the barrel, the form shown in FIGURE 5 can be made to function either in a manner that will result in the piston moving rearward upon aspiration, drawing the product of aspiration into the chamber ahead of the piston as described above, or, if desired, in a manner that will permit the perforation or slit in the membrane to open before the pressure is suflicient to move the piston rearward in the barrel, thus permitting the product of aspiration to be drawn through the perforations or slits and into the medicament chamber 50 rearward of the membrane.

FIGURE 6 illustrates a variant of the hypodermic syringe cartridge shown in FIGURE 5 wherein, by varying the placement of the venting membrane piston 22 shown in FIGURE 5, the venting piston may be used as a separator between two substances, each contained within the barrel of the syringe, which it is desired to keep separate until the user wishes to mix them. The difference between this syringe cartridge and the form shown in FIGURE 5 lies in the positioning of the venting piston separator in this form sufliciently rearward in the barrel to provide a chamber 51 of substantial size ahead of the floating venting piston as well as one 50 behind it. In operation of this form, the venting separjator would be placed first into the barrel of the cartridge at the desired position, leaving suflicient space forward and rearward of the membrane to contain the desired quantities of each of the two substances to be packaged in the cartridge. The forward chamber 51 may then be filled and a suitable closure applied to the forward end of the syringe (such closures may consist of a venting stopper of any of the forms shown in FIG- URES 1, 2, 3 or 4. The rearward chamber 5%) may then be filled with whatever substance it is desired to package in that chamber, and that chamber may be closed by insertion of a suitably vented plunger piston 69. Or the order of filling the rearward and forward chambers may be reversed if desired.

As a further alternative, as shown in FIGURE 7, a venting piston 22 of the sort illustrated in FIGURE 5 may first be inserted into the barrel and positioned adjacent the neck; the substance to be packaged in the forward chamber 52 may then be inserted from the rear of the cartridge and a second venting piston 22a, suitably vented, may be introduced from the rear of the barrel to serve as a separator, whereupon the rearward chamber 56 may be filled and closed by the insertion of a plunger piston 6i) suitably vented. The closed valves provided by the perforations or slits in the membrane of the venting piston separator 22:: would prevent commingling of the two substances until the user applies pressure by actuation of the plunger piston to force the substance in the rearward chamber 5t) through the perforation or slit in the membrane 5 of the venting piston separator 22a into the forward chamber 52, where it may be mixed with the substance contained in that chamber, and thereafter, by means of continued forward pressure on the plunger piston, the mixture may be ejected through the venting means 22 at the forward end of the syringe and through the needle into the object of the injection.

The drawings show a cannula in the form of a hypodermic needle 39 attached to the container by a connector 13 having two inturned flanges, one bearing against the forward face of a flanged needle hub 31 or a ferrule (31, ex needle) adapted for removable attachment of a hypodermic needle, the other bearing against the outer rearward shoulder of the lip of a necked portion of the container. Other means of attaching a cannula or hypodermic needle to a container are known and may be used in conjunction with any of the forms of the invention herein described.

What is claimed is:

1. A container which has a transparent cylindrical portion communicating with an opening at one end and which is adapted to be filled or emptied by increasing or reducing its internal volume, said container having ventable closure means consisting of a floating piston mounted reciprocally in said transparent cylindrical portion of said container, said floating piston including an annulus with a central cylindrical opening coaxial with said cylindrical portion of said container and an elastic membrane closing said central cylindrical opening of said floating piston said membrane being perforated, said membrane and each perforation therein being so dimensioned that each said perforation will remain closed to seal said transparent cylindrical portion against the passage of liquid, gaseous or powdered materials when subjected to positive or negative pressures within said container that are less than those created by actuation of the means of increasing or decreasing the internal volume of said container in a manner adapted to draw material into said container or to eject its contents but is adapted to open inward when subjected to negative pressure within said container equal to or greater than that created by actuation of the means of increasing the internal volume of said container in a manner adapted to draw material into said container and to open outward when subjected to positive pressure within said container equal to or greater than that created by actuation of the means of decreasing the internal volume of said container in a manner adapted to eject its contents.

2. The construction of claim 1 wherein said container is tubular and said means of increasing or decreasing its volumeis a plunger piston, mounted reciprocally within said container.

3. The construction of claim 1 wherein said floating piston is restricted against forward movement but is free to move rearward within said container.

4. The construction of claim 1 wherein said container is a tubular hypodermic syringe cartridge having a flanged neck portion at one end, said membrane being positioned rearward of the annular shoulder formed by said neck portion, said floating piston having space to move rearwardly in said cartridge and having its forward movement restricted by said shoulder.

5. The construction of claim 3 wherein said membrane, each said perforation and said floating piston are so dimensioned that, forward motion of said floating piston being restricted, each said perforation will open outward when subjected to positive pressure within said container equal to or exceeding that created by actuation of the means of decreasing the internal volume of said container for the purpose of ejecting its contents, but said floating piston will move rearward in said container when subjected to negative pressure within said container equal to or exceeding that created by actuation of the means of decreasing the internal volume of said container for the purpose of drawing material into said container.

6. A hypodermic syringe construction having a transparent tubular barrel providing a chamber for medicament, means of affixing a hypodermic. needle mounted at one end of said barrel, a plunger piston reciprocally mounted within said barrel adjacent the other endthereof, a floating piston mounted intermediate said plunger.

piston and said needle, dividing said chamber into aligned compartments, said floating piston including an annulus having a central cylindrical passage coaxial with said barrel, and an elastic membrane closing said passage, said membrane being perforated, said membrane and each perforation thereon being so dimensioned that each said perforation will remain closed to seal off the passage of liquid, gaseous, or powdered material through each said perforation under negative or positive pressures within said chamber less than those created by actuation of the plunger piston in a manner adapted to draw material into sm'd chamber or eject its contents, but, forward movement of said floating piston being restricted, will open outward when subject to positive pressures within said container equal to or exceeding those created by actuation of the plunger piston in a manner adapted to eject the contents of said chamber, and will remain closed and cause said floating piston to move rearward in said barrel when subjected to negative pressures within said chamber equal to or exceeding those created by actuation of the plunger piston in a manner adapted to draw material through said needle into said barrel.

7. The construction of claim 6 wherein at least one additional perforated membrane, mounted across and closing the passage of an additional floating piston, is mounted reciprocally in said chamber, dividing said chamber into aligned compartments separated by said additional perforated membrane.

8. The construction of claim 7 wherein a liquid or gaseous substance is contained in at least .one of said aligned compartments and a liquid, dry, powdered or gaseous substance is contained in at least one other of said aligned compartments.

9. The construction of claim 6 wherein a hypodermic needle is aflixed at said one end of said barrel.

(References on following page) References Cited in the file of this patent UNITED STATES PATENTS Cressler May 7, 1929 Cressler May 7, 1929 5 Fox et a1 July 14, 1931 Nevin Jan. 12, 1932 Hein Oct. 3, 1933 Lockhart Dec. 11, 1951 Brown Aug. 19, 1952 10 Parsons et a1 Aug. 18, 1953 10 Huber Sept. 14, 1954 Ashkenaz Apr. 1, 1958 Cohen Aug. 19, 1958 Damn et a1. Ian. 27, 1959 FOREIGN PATENTS Great Britain Apr. 24, 1957 France May 6, 1903 OTHER REFERENCES Germany, E6112V111 d/30K, September 13, 1956. 

1. A CONTAINER WHICH HAS A TRANSPARENT CYLINDRICAL PORTION COMMUNICATING WITH AN OPENING AT ONE END AND WHICH IS ADAPTED TO BE FILLED OR EMPTIED BY INCREASING OR REDUCING ITS INTERNAL VOLUME, SAID CONTAINER HAVING VENTABLE CLOSURE MEANS CONSISTING OF A FLOATING PISTON MOUNTED RECIPROCALLY IN SAID TRANSPARENT CYLINDRICAL PORTIONG OF SAID CONTAINER, SAID FLOATING PISTON INCLUDING AN ANNULUS WITH A CENTRAL CYLINDRICAL OPENING COAXIAL WITH SAID CYLINDRICAL PORTION OF SAID CONTAINER AND AN ELASTIC MEMBRANCE CLOSING SAID CENTRAL CYLINDRICAL OPENING OF SAID FLOATING PISTON SAID MEMBRANCE BEING PERFORATED, SAID MEMBRANE AND EACH PERFORATION THEREIN BEING SO DIMENSIONED THAT EACH SAID PERFORATION WILL REMAIN CLOSED TO SEAL SAID TRANSPARENT CYLINDRICAL PORTION AGAINST THE PASSAGE OF LIQUID, GASEOUS OR POWDERED MATERIALS WHEN SUBJECTED TO POSITIVE OR NEGATIVE PRESSURES WITHIN SAID CONTAINER THAT ARE LESS THAN THOSE CREATED BY ACTUATION OF THE 